AcWing 789. 数的范围

#include <bits/stdc++.h>
using namespace std;
const int N=1e6+10;
int q[N];
int check_min(int x,int l,int r){

    while(l<r){
            int mid=l+r>>1;
            if(q[mid]>=x) r=mid;else l=mid+1;
    }
    //cout<<"l:"<<l<<" r:"<<r<<endl;
    if(q[l]!=x) return -1;
    return l;
}
int check_max(int x,int l,int r){
    while(l<r){
            int mid=l+r+1>>1;
            if(q[mid]<=x) l=mid;else r=mid-1;
    }
    //cout<<"l:"<<l<<" r:"<<r<<endl;
    if(q[l]!=x) return -1;
    return l;
}
int main(){
    int n,m;
    scanf("%d%d",&n,&m);
    for(int i=0;i<n;i++)
        scanf("%d",&q[i]);

    while(m--){
        int x;
        scanf("%d",&x);
        cout<<check_min(x,0,n-1)<<" "<<check_max(x,0,n-1)<<endl;
        //check_min(x,0,n-1);check_max(x,0,n-1);
    }
    return 0;
}